The honor of giving the Mayo Memorial Lecture at Dartmouth College is not one that can be taken lightly, for we must think in terms of two of the greatest physicians in American medicine. From a small clinic developed by their father shortly before 1900, Doctor Will and Doctor Charles, as they were always known to their contemporaries, established the Mayo Clinic in Rochester, Minn., and later the Mayo Foundation for Medical Education. Expert craftsmen in surgery, Doctor Will, the elder, cultivated the field of abdominal surgery; his younger brother, Doctor Charles, paid particular attention to the treatment of goiter, a disease prevalent in the Midwest. These country doctors established a clinical and educational center, soon to become known throughout the United States and ultimately around the world. The brothers, however, were not satisfied with just serving their community as competent surgeons; they also thought in terms of raising the